The purpose of the proposed study is to determine whether a substance from bacteria resembling the human placental hormone, human chorionic gonadotropin (hCG), actually is hCG. The specific aims are a) to characterize the gonad-stimulating activity of the factor produced by the microorganism, Staphylococcus simulans RU-1 strain b) to determine physicochemical properties and complete or partial amino acid sequence of the factor and compare them with those of hCG and the luteinizing hormone, LH c) to detect the gene(s) encoding for the factor by the application of the Southern hybridization method and d) to locate the gene(s) either in plasmid or chromosomal DNAs. Subsequently the nucleotide sequence of the gene(s) will be analyzed. Nucleotide sequence of the gene(s) will be correlated with the amino acid sequence of the factor and compared with the base sequence of hCG genes. The results will establish the identity of the bacterial factor and show the degree of similarity to hCG. The demonstration that the factor is the same as or a structural variant of choriogonadotropin would indicate that eutharian hormones can be produced by a prokaryote. We plan to investigate the role of production of this factor as an adaptive mechanism for certain strains of microorganisms. Our hypothesis is that the bacterial factor may act as a generalized immunosuppressant. The information generated will shed light on the host-microorganism relationship and clarify the role that genes encoding for that factor play in adaptation and survival of the species. The invasion of certain strains in patients with debilitating diseases may involve the production of BGF. Detection and localization of the genes encoding for BGF in the mirobial genome will bear on the important issue of the origin of the genes and delineate the conditions for their activation. Determination of the base sequence of the genes may uncover evidence suggesting the existence of a common ancestor for BGF and hCG, carrying important implications about the evolution of mammalian hormones.